The inoculum used was secondary effluent obtained from a laboratory rolling tube treatment unit which is fed on 100% settled sewage obtained from Newton Abbot sewage treatment works, which treats sewage of predominantly domestic origin. This effluent was collected overnight on the day before the start of the test, after which it was filtered through a GF/C filter paper to remove any solids and sparged with nitrogen to reduce its dissolved inorganic carbon content to less than 1%. During sparging, its pH was maintained within the range 6.8-7.2 using mineral acid and alkali.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

ThIC

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

The method uses septum sealed bottles with a 156 mL volume and measures the evolution of CO2 generated as a result of mineralisation of organic carbon arising from biodegradation. Each test bottle was filled with 95 mL inoculated mineral medium, made up to 100 mL with test substance or reference substance solution and/or water as applicable. After sparging the effluent was added to the test medium at 100 mL per litre of final medium. The bottles were sealed with butyl rubber septa and aluminium crimp caps and placed in an orbital incubator at a nominal test temperature of 20 ± 2°C. They were incubated for 28 days in the dark whilst being shaken at a nominal 150 rpm. Biodegradation was monitored by regular analysis of sacrificial test bottles to determine the amount of inorganic carbon evolved.

Reference substance:

aniline

Key result

Parameter:

% degradation (inorg. C analysis)

Value:

100

Sampling time:

28 d

Details on results:

The percentage biodegradation is expressed as a ratio of evolved carbon dioxide to the initial theoretical carbon added as test substance

Results with reference substance:

The reference substance, aniline, degraded by 100% (based on theoretical carbon concentration) during the 28 days of the test, confirming the viability of the inoculum. The total carbon content of the 258 mg aniline stock solution (theoretical 200 mg C/L) was measured as 166 mg C/L.

Test Article 97-215-03 meets the criterion outlined in the OECD guidelines, and can, therefore, be considered readily biodegradable.

Inorganic Carbon measurement and biodegradation results

Bottle contents

Inorganic Carbon (mg C/L)

Day 4

Day 7

Day 14

Day 21

Day 28

Blank control

0.59

0.80

1.1

1.0

1.5

0.65

0.76

1.0

1.1

1.4

0.67

0.75

1.1

1.1

1.7

Mean

0.64

0.77

1.1

1.1

1.5

Aniline (10 mg C/L)

6.1

7.0

8.6

8.1

9.7

5.9

7.6

8.7

7.9

9.6

5.7

6.7

8.0

7.8

8.8

Mean

5.9

7.1

8.4

7.9

9.4

Mean (blank corrected)

5.3

6.3

7.4

6.9

7.8

Total inorganic C in test bottle (mg)

0.84

1.0

1.2

1.1

1.3

% Biodegradation

84

101

118

110

125

Zenolide (10 mg C/L)

4.5

5.3

7.7

7.4

8.9

4.7

5.6

7.7

8.3

8.5

5.3

5.6

7.9

7.5

8.6

Mean

4.8

5.5

7.8

7.7

8.7

Mean (blank corrected)

4.2

4.7

6.7

6.7

7.1

Total inorganic C in test bottle (mg)

0.67

0.76

1.1

1.1

1.1

% Biodegradation

67

76

107

107

114

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

A 100% biodegradation of the test substance was observed within the 28-day test period in the CO2 evolution test fulfilling the 10-day time window criterion for ready biodegradable compounds.

Executive summary:

The ready biodegradability of the substance was determined in a study conducted according to OECD TG 301B (CO2 evolution test) and GLP. In this study, 10 mg/L of test substance (based on ThIC) is exposed for 28 days to secondary activated sludge from a wastewater plant treating predominantly domestic wastewater. After the 28-day exposure period 100% of the test substance was biodegraded. The pass level of 60% was reached within 4 days after the start of the test, and thus the 10-day time window criterion was met. Based on these findings, the test substance may be classified as readily biodegradable.

Description of key information

Oenanthic ether is readily biodegradable based on read across from Zenolide, which is tested in an OECD TG 301B.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Ready biodegradability of Oenanthic ether is based on read-across from Zenolide's biodegradation information of which the summary is presented below.

Zenolide's ready biodegradability:

For Zenolide, the ready biodegradability of the substance was determined in a studyconducted according to OECD TG 301B (CO2 evolution test) and GLP. In this study, 10 mg/L of test substance (based on ThIC) is exposed for 28 days to secondary activated sludge from a wastewater plant treating predominantly domestic wastewater. After the 28-day exposure period 100% of the test substance was biodegraded. The pass level of 60% was reached within 4 days after the start of the test, and thus the 10-day time window criterion was met. Based on these findings, the substance is qualified as readily biodegradable.

Biodegradation of Oenanthic ether based on read across from data available for Zenolide (CAS #54982-83-1).

Introduction and hypothesis for the analogue approach

Oenanthic ether consists of 3 main constituents and a number of impurities. All are ethyl esters, despite the name ether, of long chain carboxylic acids. The major constituent has a C12 chain, the two minor ones have C14 and C16 saturated carbon chain. For Oenanthic ether there are no experimental biodegradation data available.In accordance with Article 13 of REACH, lacking information can be generated by means other than experimental testing, i.e. applying alternative methods such as QSARs, grouping and read-across.For assessing the biodegradation of Oenanthic ether, the analogue approach is selected becausefora close structural analogue, Zenolide, experimental data is available which can be used for read across.

Hypothesis: Oenanthic ether has the same ready biodegradability as Zenolide. The ready biodegradability of Zenolide is considered to be representative for all constituents and impurities of Oenanthic ether.

Available information: For Zenolide, the ready biodegradability of the substance was determined in a study conducted according to OECD TG 301B (CO2 evolution test, Rel. 1). In this study, 10 mg/L of test substance (based on ThIC) was exposed for 28 days to secondary activated sludge from a wastewater plant treating predominantly domestic wastewater. After the 28-day exposure period 100% of the test substance was biodegraded. The pass level of 60% was reached within 4 days after the start of the test, and thus the 10-day time window criterion was met and therefore Zenolide is readily biodegradable.

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical(s) are shown in the data matrix, including physico-chemical properties and available environmentalfateinformation. A full list of constituents and impurities of Oenanthic ether, including information relevant for read-across, is given in Appendix 1.

Purity / Impurities

The purity, and unidentified impurities, of Oenanthic ether and Zenolide are not expected to influence the potential for biodegradation.

Analogue approach justification

According to Annex XI 1.5 read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group.When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation, which is presented below.

Analogue selection: For Oenanthic ether Zenolide was selected as an analogue being a similar fatty acid type of acetic (ethyl) ester.

Structural similarities and differences: All constituents of Oenanthic ether and Zenolide contain ethyl esters and a long alkane chain (C8-C18 and C12, respectively) and therefore have a similar backbone and functional group: i.e. esters of long chain carboxylic acids. The difference is that all constituents of Oenanthic ether have linear alkyl chains, while Zenolide has a cyclic aliphatic alkyl chain, connected by Ethylene glycol, which will not affect the biodegradability.

Bioavailability: Oenanthic ether and Zenolide are fatty acid type of esters and based on their log Kows Oenanthic ether may be somewhat less bioavailable compared to Zenolide. After the ester cleavage this difference is not existing anymore and therefore will not affect the biodegradability.

Biodegradable fragments: Firstly the ester bond will be cleaved in both Oenanthic ether and Zenolide by abundantly available carboxyl esterases (Wheelock et al, 2008) resulting in fatty acids of >=C8 and ethanol in the case of Oenanthic ether and Ethylene glycol for Zenolide. These acids and alcohols all are readily biodegradable. This is further supported by Fisk et al. (2009) who has reviewed long chain alcohols for their biodegradability. During metabolism primary alcohols and acids can be easily converted into each other.

Further support for ready biodegradability using BIOWIN predictions:

BIOWIN (v4.10) predictions are made for both the Oenanthic ether and Zenolide to provide further insight on the biodegradation potential of these substances and the possible effect of structural differences on biodegradation. Only the BIOWIN modules 5 (‘MITI-linear’) and 6 (‘MITI-non-linear’) are used because these two models are based on ready biodegradability tests, which is the endpoint to be predicted.

Table: BIOWIN predictions for Oenanthic ether and Zenolide and the contribution of the fragments for the prediction of ready and non-ready biodegradability

Constituent/structural analogue

BIOWIN 5

BIOWIN 6

Ethyl octanoate

0.8901

0.9545

Ethyl decanoate

0.9055

0.9566

Ethyl dodecanoate

0.9208

0.9586

Ethyl tetradecanoate

0.9362

0.9605

Ethyl hexadecanoate

0.9516

0.9623

Ethyl octadecanoate

0.9670

0.9641

Ethyl (9Z)-octadec-9-enoate

0.8865

0.9273

Ethyl (9Z,12Z)‐octadeca‐,12‐di enoate

0.8060

0.8584

ZENOLIDE (structural analogue)

0.8737

0.9456

From these BIOWIN predictions it can be seen that the different constituents of Oenanthic ether as well as Zenolide have BIOWIN scores all exceeding 0.8 probability, which is well above the cut-off value of 0.5 and are therefore predicted to be readily biodegradable with high certainty.

Uncertainty of the prediction: As presented aboveZenolide has a lower log Kow value and a higher water solubility than Oenanthic ether. The substance is therefore likely to have higher bioavailability towards microorganisms in STP sludge and in the environment. This will not impact the ready biodegradability because long-chain hydrocarbons (hexadecane, ECHA website), alcohols (Fisk et al. 2009) and acids (SIDS dossier on Dodecanedioc acid) are known to be readily biodegradable. There are no other remaining uncertainties than already discussed above.

Data matrix

The relevant information on physico-chemical properties and environmental fate properties are presented in the data matrix below.

Conclusions for biodegradability

For Oenanthic ether no information on ready biodegradability is available and Zenolide information on this endpoint is used for read across.When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation. This documentation is presented in the current. Zenolide is readily biodegradable and therefore Oenanthic ether is also readily biodegradable based on similarities in structure and degradation pathways.

Final conclusion on biodegradation: Oenanthic ether is readily biodegradable.

Data matrix presenting the information relevant for read across toOenanthic ether from Zenolide

References

Data matrix:Overview of data available for the different constituents of Oenanthic ether and the structural analogue Zenolide to support the read across for biodegradation

Chemical names for

Oenanthic ether#

ethyl octanoate (C8*)

ethyl decanoate (C10*)

ethyl dodecanoate (C12*)

ethyl tetra-decanoate (C14*)

ethyl hexa-decanoate (C16*)

ethyl octa-decanoate (C18*)

ethyl (9Z)-octadec-9-enoate (C18*)

ethyl (9Z,12Z)‐octadeca‐,12‐di enoate (C18*)

Zenolide

(‘C12’)

Target

Source

CAS#

106-32-1

110-38-3

106-33-2

124-06-1

628-97-7

111-61-5

544-35-4

111-62-6

5982-83-1

Structure

% in product

<10

<10

35-55

15-30

5-15

<10

<10

<10

EC No.

945-734-0#

259-423-6

Vp (Pa)

0.12 meas)#

31.4

(est.)

5.70

(est.)

1.17

(est.)

0.34

(est.)

0.036

(est.)

0.0084

(est.)

0.0081

(est.)

0.0067

(est.)

0.028

(exp.)

WS (mg/L)

1.6 (meas)#

45.6

(est.)

4.8

(est.)

0.41

(est.)

0.037

(est.)

0.0037

(est.)

0.0004

(est.)

0.0006

(est.)

0.0009

(est.)

75

(exp.)

Log Kow

4.6 (meas)#

3.8

(est.)

4.8

(est.)

5.8

(est.)

6.8

(est.)

7.7

(est.)

8.4

(est.)

8.5

(est.)

8.3

(est.)

3.65

(exp.)

Fate

Readily Biodegradability

Readily (Read across)

Readily (Read across)

Readily (Read across)

Readily (Read across)

Readily (Read across)

Readily (Read across)

Readily (Read across)

Readily (Read across)

Readily biodegradable (OECDTG 301F)

*The C’s are related to the chain length not the overall number of Cs (as would be presented in the Empirical formula); (est.) = estimated using EpiSuite; (exp.) = experimental;#In this column the values are for Oenanthic ether as such.

Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.

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